The present invention relates to testing wireless transceivers, and in particular, to testing wireless data packet signal transceivers.
Many of today's electronic devices use wireless technologies for both connectivity and communications purposes. Because wireless devices transmit and receive electromagnetic energy, and because two or more wireless devices have the potential of interfering with the operations of one another by virtue of their signal frequencies and power spectral densities, these devices and their wireless technologies must adhere to various wireless technology standard specifications.
When designing such devices, engineers take extraordinary care to ensure that such devices will meet or exceed each of their included wireless technology prescribed standard-based specifications. Furthermore, when these devices are later being manufactured in quantity, they are tested to ensure that manufacturing defects will not cause improper operation, including their adherence to the included wireless technology standard-based specifications.
For testing these devices following their manufacture and assembly, current wireless device test systems employ a subsystem for analyzing signals received from each device. Such subsystems typically include at least a vector signal analyzer (VSA) for analyzing signals produced by the device. The analyses performed by the VSA are generally programmable so as to allow each to be used for testing a variety of devices for adherence to a variety of wireless technology standards with differing frequency ranges, bandwidths and signal modulation characteristics.
As part of the manufacturing of wireless communication devices, one significant component of product cost is manufacturing test cost. Typically, there is a direct correlation between the cost of test and the time required to perform such test. Thus, innovations that can shorten test time without compromising test accuracy or increasing capital equipment costs (e.g., increasing costs due to increasing sophistication of test equipment, or testers) are important and can provide significant cost savings, particularly in view of the large numbers of such devices being manufactured and tested.
Among others, one test often conducted involves testing the signal link between a device under test (DUT) and a tester when connected through a conductive signal path (typically in the form of a radio frequency (RF) transmission line (e.g., coaxial cable) having the characteristic impedance of the system) to a reference signal source to allow conveyance and communication of data packets between the reference device and the DUT. Such signal link tests are based on the number of data packets conveyed that are received by the DUT without error during a known or prescribed time interval.
Ordinarily, this type of test includes conveyance of data packets from the reference device to the DUT, which, in turn, responding with responsive data packets indicating whether a correct data packet has been received. The responsive data packets are typically in the form of a confirmation data packet, such as an acknowledgement (ACK) data packet.
However, absent additional circuitry or subsystems for capturing and retaining the data packets sent between the two devices (e.g., the reference data packets from the referenced device and the confirmation data packets from the DUT), it cannot be determined whether faulty packets were received due to faulty packets having been transmitted originally from the reference device, or correct packets had been received but received in a faulty manner by the DUT.
Accordingly, it would desirable to have a technique for capturing packets conveyed between the devices and for retaining those packets in response to which no confirmation packet is returned, or for which a confirmation packet is returned but after a prescribed time limit has been exceeded.